Currently, two basic ways are known of improving the process for recovery of rose oil from the vegetable feedstock, namely: thermal fermentation of the feedstock based on the effect of proper enzymes of rose plants, and the use of cultures of microorganisms. However, both groups of processes feature a number of essential disadvantages and do not enable a sufficiently complete recovery of the final product with high quality characteristics.
A process is known in the art for producing rose oil by way of thermal incubation of the vegetable feedstock, such as rose flowers based on the effect of proper enzymes of the plant (autofermentation). The starting stock is combined with a 15% solution of NaCl or water in a ratio of the feedstock:water of 1:2.5 respectively and maintained at the temperature of 45.degree. C. for 4 to 6 hours or at a temperature of from 22.degree. to 27.degree. C. for 6 to 48 hours. The recovery of rose oil is effected by hydrodistillation for 6-7 hours, followed by adsorption of the oil in a column with activated carbon and desorption with ethyl ether. (Cf. "Essential-Oil Industry of Georgian SSR", Tbilisi, 1968; "Applied Biochemistry and Microbiology", vol. XII, issue 5, 1976 /in Russian/).
The technique employed is rather simple, though possessing such disadvantages as a low yield of oil (0.06-0.013%) and a poor quality of the final product. The content of monoterpene alcohols--the most valuable components--is only 8.5 to 12.0%, the content of .beta.-phenylethyl alcohol--the less valuable component--is as high as 85-90%.
Also known in the art is a process for producing rose oil based on the effect of enzymes of plants (rose flowers) under anaerobic conditions without the addition of water. The process of pre-treatment of the feedstock is effected in hermetically sealed polyethylene bags at room temperature for 48 hours. The subsequent operations comprise treatment of the material with petroleum ether in extraction columns at room temperature and recovery of absolute ethereal rose oil.
The yield of rose oil produced in this manner is at the level of 0.03% by weight of the starting feedstock. Quality of the oil in respect of terpene alcohols and .beta.-phenylethyl alcohol is higher than that of rose oil produced by way of a thermal incubation with a subsequent hydrodistillation.
Therefore, this prior art process features a very low yield of rose oil and instability of the process conditions. Furthermore, the process also features certain technological difficulties such as the necessity of creating anaerobic conditions for enzymes, i.e. collect the starting feedstock and hermetically seal polyethylene bags directly at the plantations. All this is associated with large additional expenses for the materials and equipment. This process does not enjoy a commercial implementation (USSR Inventor's Certificate No. 478057, Cl. Int. C 11 B 9/02, published July 25, 1975, Bulletin No. 27).
A microbiological process is also known in the art for the production of rose oil involving a preliminary treatment of the rose stock by means of cultures of special strains of microorganisms of the genus Aspergillus, Licoperdon, Monilla, Saccharomyces. As the starting stock use is made of the waste products resulting from hydrodistillation; the process is conducted at a temperature within the range of from 25.degree. to 40.degree. C. and the pH value of 4.5 for 26 hours.
The recovery of rose oil from the wastes is effected by a repeated hydrodistillation, followed by adsorption and desorption of the oil and distilling-off of the solvent.
The process makes it possible to recover an additional amount of rose oil (about 0.02% by weight of the starting stock) from the waste products (cf. Bulgarian Pat. No. 15312, published June 25, 1971).
This process, however, features but a low yield and poor quality of the desired product. Moreover, the process has certain difficulties such as the necessity of preparation of the inoculation culture of fungi under the conditions of the rose oil manufacture, additional expenses for the preparation of the feedstock-dehydration of the waste products, as well as process instability and long duration.
This process does not enable the production of rose oil having standard quality.